Add support for multiple private links to one ClickHouse service

[smstone]

The Terraform provider currently supports the ability to have a private link setup to a given ClickHouse service, however a customer may require multiple private links from more than one VPC to a given ClickHouse service. Currently, when setting up multiple private links from different VPCs to a given ClickHouse service via the Terraform provider, inconsistent results are seen (overwriting of existing private link setup, etc.) The API supports this, however this is currently a limitation in this provider.

[whites11]

Problem is this block of code.

We introduced it to prevent a bug during 0.3.0 to 1.0.0+ upgrade.

This is described here: https://registry.terraform.io/providers/ClickHouse/clickhouse/latest/docs#upgrading-to-version--100-of-the-clickhouse-terraform-provider

[whites11]

fixed in 1.3.1